Refrigeration and air conditioning systems generally include a compressor, a condenser, an expansion valve or its equivalent, and an evaporator. These components are coupled in sequence to define a continuous flow path. A working fluid typically called a refrigerant flows through the system and alternates between a liquid phase and a vapor or gaseous phase.
A variety of compressor types have been used in refrigeration systems, including, but not limited to, reciprocating compressors, screw compressors and rotary compressors. Rotary compressors can include both the vane type compressors, the scroll machines as well as other rotary styled compressors.
Scroll machines are becoming more and more popular for the compressor of choice in both refrigeration as well as air conditioning applications due primarily to their capability for extremely efficient operation. Scroll compressors are typically constructed using two scroll members with each scroll member having an end plate and a spiral wrap extending from the end plate. The spiral wraps are arranged in an opposing manner with the two spiral wraps being interfitted. The scroll members are mounted so that they may engage in relative orbiting motion with respect to each other. During this orbiting movement, the spiral wraps define a successive series of enclosed spaces, each of which progressively decreases in size as it moves inwardly from a radially outer position at a relatively low suction pressure to a central position at a relatively high discharge pressure. The compressed gas exits from the enclosed space at the central position through a discharge passage formed through the end plates of one of the scroll members.
An electric motor or another power source is provided which operates to drive one of the scroll members via a suitable drive shaft affixed to the motor rotor. In a hermetic compressor, the bottom of the hermetic shell normally contains an oil sump for lubricating and cooling the various components of the compressor.
Relative rotation between the two scroll members is typically controlled by an anti-rotation mechanism. One of the more popular anti-rotation mechanisms is an Oldham coupling, which is keyed to either the two scroll members or to one of the scroll members and a stationary component such as a bearing housing. While Oldham couplings are a popular choice, other anti-rotation mechanisms may also be utilized.
Due to the increasing popularity of scroll compressors, the continued development of these compressors has been directed towards designs that reduce size, reduce complexity and reduce cost without adversely affecting the performance of the scroll compressor.
The present invention provides the art with a scroll compressor design that provides the design objectives detailed above. All of the embodiments of the present invention incorporate an orbiting and a non-orbiting scroll member that are designed with a rapid compression scroll wrap profile. This scroll wrap profile provides the advantages of a shorter wrap, lower vane aspect ratios and a reduction in the amount of machining for the scroll members. The non-orbiting scroll member is integrated with the main bearing housing, which reduces both cost and complexity. Another feature of the present invention is that the drive shaft extends through the central portion of each of the scroll members and the counterweight is positioned above both of the two scroll members. This allows for the option of positioning the counterweight in closer proximity to the center of gravity of the orbiting scroll member, thus allowing for the reduction in its size. With the counterweight positioned above the two scroll members, the counterweight can also be designed to limit axial movement of the scroll members and it can also be designed to function as a rotary discharge valve.
In one design option, an Oldham coupling is used as the anti-rotation device. In another design option, the Oldham coupling is replaced with a swing link. In yet another design option, the drive shaft is supported by a bearing located above both scroll members, rather than being unsupported at its upper end as is the case in other designs.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.